raise

Python raise as a Function

Raise exceptions with a function instead of a statement.

Provides a minimal and portable interface for raising exceptions with all the advantages of functions over syntax.

Versioning

This library's version numbers follow the SemVer 2.0.0 specification <https://semver.org/spec/v2.0.0.html>_.

Installation

::

pip install raise

Usage

Import raise_:

.. code:: python

from raise_ import raise_

Raise an exception:

.. code:: python

raise_(Exception('foo'))

Raise an exception with a traceback:

.. code:: python

raise_(Exception('foo'), traceback)

Raise in a lambda:

.. code:: python

lambda x: x if x > 0 else raise_(ValueError('x is too small!')) 

And of course because raise_ is a function, you can combine it with functools.partial and other functional programming libraries and techniques for many more uses.

Surprises

raise_ clears __traceback__ if you don't pass in a traceback, same as if you passed in None. If you want the Python 3 behavior of reusing the __traceback__, you should explicitly pass it in:

.. code:: python

raise_(exception, exception.__traceback__)

Or, if you want to gracefully degrade on Python implementations which do not have __traceback__ on their exceptions:

.. code:: python

raise_(exception, getattr(exception, '__traceback__', None))

Portability

Portable to all releases of both Python 3 and Python 2.

(The oldest tested is 2.5, but it will likely work on all Python 2 versions and probably on even earlier versions.)

For implementations of Python that do not support raising with a custom traceback, a "no traceback" variant is included in the source that can be installed manually.